Static pressure pad, grinding equipment and silicon wafer

Abstract

The embodiment of the present invention discloses a static pressure pad, a grinding device and a silicon wafer. The static pressure pad is used to clamp the two sides of the silicon wafer in pairs in the silicon wafer double-sided grinding device. The static pressure pad includes a substrate, an adjustment plate and a driving module. The substrate has a fixed plane facing the silicon wafer; the adjustment plate is installed on the fixed plane through the driving module, and the adjustment plate has a first plane facing the silicon wafer. The first plane is used to provide static pressure to the silicon wafer through a fluid to support one side of the silicon wafer in a non-contact manner; the driving module is used to drive the adjustment plate to tilt. The driving module is configured to drive the adjustment plate to tilt when the first plane is not parallel to the target plane where the silicon wafer is located, so that the first plane is parallel to the target plane. By adjusting the distance between the static pressure pad and the silicon wafer in real time, the stability of the grinding process is ensured and the product quality is improved.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor manufacturing, and in particular to a static pressure pad, a grinding device and a silicon wafer. Background Art

[0002] The production process of semiconductor silicon wafers usually includes processes such as crystal pulling, wire cutting, grinding, and polishing. Double-sided grinding is a grinding process used to grind the two main surfaces of the silicon wafer at the same time so that the silicon wafer has a highly flat surface. During the double-sided grinding process, a special device is required to hold the silicon wafer so that the grinding wheel can grind the two main surfaces of the silicon wafer at the same time. Usually, this holding device includes a pair of fluid static pressure supports arranged oppositely, and the silicon wafer is arranged between the two fluid static pressure supports in the vertical direction. The fluid static pressure support can form a fluid barrier between itself and the main surface of the silicon wafer so that the silicon wafer can be kept upright without contacting the two fluid static pressure supports. At the same time, the two main surfaces of the silicon wafer can be ground using the opposing grinding wheels. Compared with physical clamping, the fluid clamping method of the fluid static pressure support reduces damage to the silicon wafer and allows the silicon wafer to move (rotate) in the tangential direction relative to the surface of the fluid static pressure support with less friction.

[0003] However, in the double-sided grinding equipment, it is necessary to adjust the angle of a pair of opposing grinding wheels to adjust the flatness of the silicon wafer. During the adjustment of the grinding wheels, when the deflection angle of the left and right pair of grinding wheels is too large, the silicon wafer will be tilted when the grinding wheels directly contact the silicon wafer. Or when the above-mentioned special device is used to hold the silicon wafer, the silicon wafer will also be tilted due to the instability of the mechanical structure. In this case, since the spacing between a pair of static pressure supports is fixed and the distance between the single-sided static pressure support and the silicon wafer is fixed, the silicon wafer will come into contact with the static pressure support, causing friction between the silicon wafer and the static pressure support, which will deteriorate the flatness of the silicon wafer and even cause fragmentation. Summary of the invention

[0004] To solve the above technical problems, an embodiment of the present invention hopes to provide a static pressure pad, a grinding device and a silicon wafer, by adjusting the distance between the static pressure pad and the silicon wafer in real time during the double-sided grinding process to ensure the stability of the grinding process and improve product quality.

[0005] The technical solution of the present invention is achieved in this way:

[0006] In a first aspect, the present invention provides a static pressure pad, which is used to clamp the two sides of the silicon wafer in pairs in a silicon wafer double-sided grinding device, and the static pressure pad includes a substrate, an adjustment plate and a driving module: the substrate has a fixed plane facing the silicon wafer; the adjustment plate is installed on the fixed plane through the driving module, and the adjustment plate has a first plane facing the silicon wafer, and the first plane is used to provide static pressure to the silicon wafer through a fluid to support one side of the silicon wafer in a non-contact manner; the driving module is used to drive the adjustment plate to tilt, and the driving module is configured to drive the adjustment plate to tilt when the first plane is not parallel to the target plane where the silicon wafer is located, so that the first plane is parallel to the target plane.

[0007] Preferably, the driving module comprises a plurality of independently controllable driving rods, the driving rods being configured to be able to extend and retract along a direction perpendicular to the fixing plane, and the ends of the driving rods protruding from the fixing plane are hinged to the adjustment plate.

[0008] Preferably, at least two driving rods are evenly arranged on the substrate along the vertical direction, and the driving rods are hinged to a side of the adjustment plate away from the silicon wafer.

[0009] Preferably, the driving module further comprises a hydraulic driving unit or a pneumatic driving unit for driving the driving rod to extend and retract.

[0010] Preferably, the static pressure pad also includes a sensor and a controller, the sensor is used to sense the spatial posture of the silicon wafer to obtain the spatial position of the target plane, and the controller is configured to control the extension and retraction of the driving rod according to the spatial position of the target plane so that the first plane is parallel to the target plane.

[0011] Preferably, the sensor is a pressure sensor, and the pressure sensor is used to sense the change of the static pressure on the silicon wafer, so as to obtain the spatial posture of the silicon wafer.

[0012] Preferably, the sensor is a distance sensor, and the distance sensor is used to sense the distance between the silicon wafer and the first plane, so as to obtain the spatial posture of the silicon wafer.

[0013] Preferably, the first plane is evenly provided with a plurality of through holes for allowing the fluid to flow out, and the adjustment plate is constructed so that the fluid flowing out of each through hole can support the silicon wafer with a static pressure force of equal magnitude and direction.

[0014] In a second aspect, the present invention provides a grinding device for double-sided grinding of silicon wafers, the grinding device comprising: a carrier for supporting the silicon wafer in a vertical direction; two grinding wheels symmetrically arranged about the carrier; and the two static pressure pads symmetrically arranged about the carrier.

[0015] In a third aspect, the present invention provides a silicon wafer obtained by using the above-mentioned grinding device.

[0016] An embodiment of the present invention provides a static pressure pad, a grinding device and a silicon wafer. The static pressure pad includes a fixed substrate, an adjustment plate arranged on the substrate and a driving module. The adjustment plate is used to provide equal supporting force to each force point on the silicon wafer through a fluid. The adjustment plate can be tilted under the drive of the driving module so that the adjustment plate and the silicon wafer are always in a parallel state, thereby ensuring that the static pressure pad will not touch the silicon wafer when the silicon wafer is tilted significantly, thereby avoiding the occurrence of fragments and / or damage to the static pressure pad. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of a vertical grinding device in the prior art;

[0018] Figure 2 A schematic diagram of the structure of a polishing pad according to an embodiment of the present invention;

[0019] Figure 3 A schematic diagram of using a polishing pad according to an embodiment of the present invention to clamp a tilted silicon wafer;

[0020] Figure 4 A schematic diagram of using a polishing pad in an embodiment of the present invention to clamp a silicon wafer;

[0021] Figure 5 The figure is a schematic diagram of the shape of a polishing pad in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0023] As the diameter of silicon wafers increases and the feature size of integrated circuits decreases, higher requirements are placed on the flatness and cleanliness of the silicon wafer surface, and higher requirements are placed on the surface damage of silicon wafers. Double-sided grinding refers to grinding both sides of a silicon wafer at the same time, thereby producing a silicon wafer with a highly flat surface. During double-sided grinding using a vertical grinding device, a silicon wafer clamping device is required to keep the silicon wafer upright. The clamping device generally includes a pair of fluid static pressure pads, which are configured to simultaneously apply fluid pressure to the two sides of the silicon wafer placed therebetween, thereby supporting the silicon wafer in a non-contact manner. The grinding device used to grind the silicon wafer in the vertical grinding device includes a pair of grinding wheels arranged opposite to each other, and the pair of grinding wheels grind the two sides of the silicon wafer simultaneously according to a predetermined grinding track when the silicon wafer is supported by the pair of fluid static pressure pads.

[0024] When a silicon wafer is double-sided ground using a vertical grinding device, the silicon wafer may tilt as desired or undesirably. For example, if the flatness of the silicon wafer needs to be trimmed, the flatness of the surface of the silicon wafer can be trimmed by adjusting the deflection angle of the pair of grinding wheels. For details, see the attached Figure 1 , which shows a schematic diagram of a vertical grinding device in the prior art, wherein the vertical grinding device 30 includes a pair of grinding wheels 31 and a pair of fluid static pressure pads 32, the pair of fluid static pressure pads 32 non-contact support the silicon wafer W through a fluid L, the pair of grinding wheels 31 need to be deflected along the same direction at a set deflection angle to adjust the surface flatness of the silicon wafer, in this case, the pair of grinding wheels 31 will drive the silicon wafer W to also deflect at an angle of the set deflection angle, at this time, the silicon wafer W will touch the surface of the pair of fluid static pressure pads 32, affecting the quality of the silicon wafer W or causing the occurrence of fragments.

[0025] In order to solve the above technical problems, see the attached Figure 2 To Attachment Figure 4 The present invention provides a static pressure pad 10, which can determine the target plane C where the silicon wafer W is located according to the spatial posture of the silicon wafer W, and adjust the posture of the static pressure pad 10 based on the target plane C so that the static pressure pad 10 remains parallel to the target plane C. By adjusting the posture of the static pressure pad 10 in real time, the quality of the silicon wafer W is prevented from being affected or fragments are generated when the silicon wafer W is tilted. Specifically, the static pressure pad 10 includes a substrate 11, an adjustment plate 12 and a driving module 13, wherein the adjustment plate 12 is installed on the substrate 11 through the driving module 13, and the adjustment plate 12 can be tilted under the drive of the driving module 13.

[0026] The substrate 11 has a fixed plane A on the side facing the silicon wafer W, and the adjustment plate 12 is mounted on the fixed plane A through the driving module 13. The fixed plane A is located in a vertical plane, and the fixed plane A can be used as a reference plane for adjusting the inclination of the adjustment plate 12. The adjustment plate 12 has a first plane B on the side facing the silicon wafer W, and the first plane B can provide fluid static pressure to the silicon wafer W as a supporting force to maintain the silicon wafer W, so that the silicon wafer W can be supported in the axial direction without contacting any fixing device for easy grinding. The adjustment plate 12 is mounted on the fixed plane A through the driving module 13. See the attached Figure 2 At the beginning of grinding, the adjustment plate 12 is parallel to the fixed plane A, the first plane B is also located in a vertical plane, and the fluid flowing out of the first plane B horizontally supports one side of the silicon wafer W along a direction perpendicular to the first plane B. The driving module 13 is configured to drive the adjustment plate 12 to tilt relative to the substrate 11 and take the plane where the silicon wafer W is located as the target plane C, so that when the first plane B is not parallel to the target plane C, the adjustment plate 12 is tilted under the driving of the driving module 13, and the first plane B is parallel to the target plane C.

[0027] Preferably, see Appendix Figure 2 To Attachment Figure 4 The driving module 13 includes a plurality of independently controllable driving rods 131, which cooperate with each other to drive the adjustment plate 12 to tilt so as to move the first plane B to be parallel to the target plane C. One end of the driving rod 131 is arranged inside the substrate 11, and the other end is hinged to the side of the adjustment plate 12 away from the silicon wafer W. The driving rod 131 can be extended and retracted in a direction perpendicular to the fixed plane A. See the attached Figure 3 and attached Figure 4, the plurality of driving rods 131 can make the adjustment plate 12 tilt at different angles in different directions by extending and retracting different distances in a direction perpendicular to the fixed plane A, wherein the end of the driving rod 131 extending from the substrate 11 is the first end, and the first end is hinged to the adjustment plate 12, and when the first end is extended in the horizontal direction, it can drive the part of the adjustment plate 12 connected to the first end to approach the silicon wafer W in the horizontal direction, and when the first end is contracted in the horizontal direction, it can drive the part of the adjustment plate 12 connected to the first end to move away from the silicon wafer W in the horizontal direction, and when the first end drives the adjustment plate 12 to move through the above-mentioned hinged structure, the angle between the adjustment plate 12 and the driving rod 131 changes, so as to achieve the tilting of the adjustment plate 12. In the embodiment of the present invention, the number of driving rods 131 for achieving the tilting of the adjustment plate 12 is at least two. In another embodiment of the present invention, the first end is constructed into a spherical structure, and a spherical groove is provided at a portion of the adjustment plate corresponding to the first end. When the spherical structure is installed in the spherical groove, the spherical structure can rotate in any direction relative to the spherical groove.

[0028] Schematically, see Appendix Figure 3 and attached Figure 4 The number of the plurality of driving rods 131 is 4, and the four driving rods 131 are evenly arranged on the fixing plane A with equal spacing in the vertical direction, and one end of the four driving rods 131 is fixed to the substrate 11, and the other end is hinged to the side of the adjustment plate 12 away from the silicon wafer W. See the attached Figure 3 and attached Figure 4 , which shows that when the silicon wafer W is driven by a pair of grinding wheels 20 to tilt at an angle of β in the clockwise direction, the four driving rods 131 are independently extended and retracted in sequence from top to bottom, so that the adjustment plate 12 is also tilted at an angle of β in the clockwise direction, so that the first plane B of the adjustment plate 12 is parallel to the silicon wafer W. The driving module 13 also includes a driving unit for driving each driving rod 131 to extend and retract, and the driving unit can be a hydraulic driving device or a pneumatic driving device or other driving devices capable of extending and retracting the driving rod 131.

[0029] It should be noted that in the double-sided grinding device, static pressure pads 10 are provided on different sides of the silicon wafer W to provide fluid static pressure to support the silicon wafer W. For those skilled in the art, it is easy to understand that when the static pressure pads 10 on both sides of the silicon wafer W need to be tilted, the tilting directions and tilting angles of the two static pressure pads 10 are consistent, but the telescopic states of the driving rods 131 in the driving mechanisms for achieving the above tilting are different, schematically, see the attached Figure 3 and attached Figure 4The adjustment plate 12 arranged on the right side of the silicon wafer W is tilted at an angle β in the clockwise direction, and the adjustment plate 12 arranged on the left side of the silicon wafer W is also tilted at an angle β in the clockwise direction, but the telescopic states of the driving rod 131 in the driving mechanism used to realize the tilt of the two adjustment plates 12 are different.

[0030] In order to accurately obtain the specific position of the target plane C as a reference for the movement of the driving rod 131, the static pressure pad 10 also includes a sensor (not shown) and a controller (not shown). The sensor is used to sense the spatial posture of the silicon wafer W to obtain the specific position information of the target plane C. The controller is used to send a control signal to the driving module 13 according to the position information of the target plane C, so that each driving rod 131 in the driving module 13 can be extended and retracted, thereby realizing the tilt of the adjustment plate 12, so that the first plane B and the target plane C are parallel.

[0031] Specifically, the sensor is a pressure sensor, which is used to sense the static pressure on the silicon wafer W. The static pressure is stably provided by the adjustment plate 12, that is, the fluid flowing out of the adjustment plate 12 applies static pressure of equal magnitude and direction to the silicon wafer W. When the adjustment plate 12 is parallel to the silicon wafer W, the static pressures at each location on the silicon wafer W are equal in magnitude and direction; when the silicon wafer W is tilted, the adjustment plate 12 still provides static pressures of equal magnitude and direction, but the static pressure on the silicon wafer W changes due to the tilt. The pressure sensor identifies the distribution of static pressures of different magnitudes on the silicon wafer W by sensing the change in static pressure, determines that the silicon wafer W is tilted, and learns the change in the silicon wafer W relative to the previous position, and obtains a new target plane C after the silicon wafer W is tilted. The controller sends a control signal to the drive module 13 based on the new target plane C. The drive module 13 controls the drive rod 131 to extend and retract based on the control signal to tilt the adjustment plate 12, so that the first plane B is tilted to be parallel to the target plane C.

[0032] In another embodiment of the present invention, the sensor is a distance sensor, and the distance sensor is used to directly measure the distance between the target plane C at the silicon wafer W and the first plane B of the adjustment plate 12. Here, the distance refers to the straight-line distance between the target plane C and the first plane B. When the distance between any sensing point on the target plane C and the first plane B is inconsistent, it is determined that the silicon wafer W is tilted, and the spatial position of the target plane C is obtained according to the distance between each monitoring point on the first plane B and the first plane B, so as to obtain a new target plane C. Based on the new target plane C, the controller sends a control signal to the driving module 13, and the driving module 13 controls the extension and retraction of the driving rod 131 based on the control signal to drive the adjustment plate 12 to tilt, so that the first plane B tilts to be parallel to the target plane C.

[0033] Preferably, see Appendix Figure 5 , a plurality of through holes T are evenly arranged on the first plane B, and the through holes T are used to allow the fluid to flow through the first plane B to between the silicon wafer W and the first plane B under the action of pressure, so that the silicon wafer W can be supported by the hydrostatic pressure of the fluid for grinding. In fact, in the vertical double-sided grinding device, hydrostatic pressure is provided on different sides of the silicon wafer W, such as in the attached Figure 3 and attached Figure 4 As shown in FIG. 1 , the static pressure pad 10 according to the embodiment of the present invention and another static pressure pad are respectively arranged on different sides of the silicon wafer W and provide fluid static pressure for the silicon wafer W together.

[0034] The embodiment of the present invention discloses a static pressure pad 10, the static pressure pad 10 includes a substrate 11, an adjustment plate 12 and a driving module 13, the adjustment plate 12 is provided with a through hole T, the through hole T is used to allow fluid to flow out to support a silicon wafer W with static pressure of equal magnitude and direction, the driving module 13 includes at least two driving rods 131, the driving rods 131 are arranged on a fixed plane A of the substrate 11, the driving rods 131 can be extended and retracted in a horizontal direction to drive the corresponding part of the adjustment plate 12 connected to the driving rods 131 to approach or move away from the silicon wafer W, the The static pressure pad 10 also includes a sensor and a controller. When the silicon wafer W tilts, it is characterized by a change in the target plane C of the silicon wafer W in space. The sensor obtains a new target plane C, and the controller sends a control signal to the driving module 13 based on the new target plane C. The driving module 13 adjusts the extension and retraction of at least two driving rods 131 based on the control signal to make the adjustment plate 12 tilt until the first plane B of the adjustment plate 12 is parallel to the target plane C, which is used to characterize that the adjustment plate 12 is parallel to the silicon wafer W.

[0035] The static pressure pad 10 can be used to adjust the distance between the static pressure pad 10 and the silicon wafer W in real time, and the static pressure pad 10 is always kept parallel to the silicon wafer W, thereby ensuring the stability of the grinding process and improving product quality. It should be noted that when using the static pressure pad 10, the static pressure pads 10 are provided on different sides of the silicon wafer W to provide fluid static pressure to support the silicon wafer W. The static pressure pads 10 on both sides of the silicon wafer W have the same adjustment principle, and the technical effect finally achieved can make the static pressure pad 10 parallel to the silicon wafer W.

[0036] Based on the static pressure pad 10, an embodiment of the present invention further provides a grinding device, which is used for double-sided grinding of a silicon wafer W, and includes a carrier, a pair of grinding wheels, and a pair of static pressure pads 10. The carrier is used to hold the silicon wafer W in the vertical direction; the pair of grinding wheels are symmetrically arranged on both sides of the silicon wafer W with respect to the carrier; and the pair of static pressure pads 10 are symmetrically arranged on both sides of the silicon wafer W with respect to the carrier. Specifically, see the attached Figure 5 The static pressure pad 10 is configured to be crescent-shaped in shape, so that the grinding wheel can be set at the circular notch in the double-sided grinding device of the silicon wafer W. The pair of grinding wheels grinds the two main surfaces of the silicon wafer W carried by the carrier and supported by the pair of static pressure pads 10 by rotating around a common rotation axis. The grinding wheel can retract into the circular notch of the grinding pad when the silicon wafer W is not being ground.

[0037] Based on the above-mentioned grinding device, an embodiment of the present invention further provides a silicon wafer, and the silicon wafer is obtained by using the above-mentioned grinding device.

[0038] It should be noted that the static pressure pad 10 can adjust the spatial position of the first plane B based on the change of the target plane C, so that the first plane B is parallel to the target plane C, avoiding the silicon wafer W from contacting the static pressure pad 10 while providing a more uniform supporting force to the silicon wafer W. Among them, the inclination of the silicon wafer W caused by the adjustment of the grinding wheel is not the only condition that triggers the inclination of the silicon wafer W. In any case, as the silicon wafer W tilts and the target plane C changes, the static pressure pad 10 can adjust the spatial position of the first plane B in real time to ensure that the first plane B is parallel to the target plane C, thereby achieving the parallelism of the static pressure pad 10 and the silicon wafer W.

[0039] It should be noted that the technical solutions described in the embodiments of the present invention can be combined arbitrarily without conflict.

[0040] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A static pressure pad, which is used to clamp the two sides of the silicon wafer in pairs in a double-sided polishing device for silicon wafers, characterized in that: The static pressure pad includes a base plate, an adjustment plate and a drive module: The substrate has a fixed plane facing the silicon wafer; The adjustment plate is installed on the fixed plane through the driving module, and the adjustment plate has a first plane facing the silicon wafer, and the first plane is used to provide static pressure to the silicon wafer through a fluid to support one side of the silicon wafer in a non-contact manner; The driving module is used to drive the adjustment plate to tilt. The driving module is configured to drive the adjustment plate to tilt when the first plane is not parallel to the target plane where the silicon wafer is located, so that the first plane is parallel to the target plane.

2. The static pressure pad according to claim 1, characterized in that: The driving module comprises at least two independently controllable driving rods, the driving rods being configured to be able to extend and retract along a direction perpendicular to the fixing plane, and the ends of the driving rods protruding from the fixing plane are hingedly connected to the adjustment plate.

3. The static pressure pad according to claim 2, characterized in that: At least two driving rods are evenly arranged on the substrate along the vertical direction, and the driving rods are hinged to a side of the adjustment plate away from the silicon wafer.

4. The static pressure pad according to claim 2, characterized in that: The driving module further includes a hydraulic driving unit or a pneumatic driving unit for driving the driving rod to extend and retract.

5. The static pressure pad according to claim 2, characterized in that: The static pressure pad also includes a sensor and a controller, wherein the sensor is used to sense the spatial posture of the silicon wafer to obtain the spatial position of the target plane, and the controller is configured to control the extension and retraction of the drive rod according to the spatial position of the target plane so that the first plane is parallel to the target plane.

6. The static pressure pad according to claim 5, characterized in that The sensor is a pressure sensor, and the pressure sensor is used to sense the change of the static pressure on the silicon wafer, so as to obtain the spatial posture of the silicon wafer.

7. The static pressure pad according to claim 5, characterized in that: The sensor is a distance sensor, and the distance sensor is used to sense the distance between the silicon wafer and the first plane, so as to obtain the spatial posture of the silicon wafer.

8. The static pressure pad according to claim 1, characterized in that The first plane is evenly provided with a plurality of through holes for allowing the fluid to flow out. The regulating plate is constructed so that the fluid flowing out of each through hole can support the silicon wafer with static pressure of equal magnitude and same direction.

9. A grinding device for double-sided grinding of silicon wafers, characterized in that: The grinding equipment comprises: A carrier for supporting the silicon wafer in a vertical direction; two grinding wheels symmetrically arranged about the carrier; Two static pressure pads according to any one of claims 1 to 8 are arranged symmetrically with respect to the carrier.

10. A silicon wafer, characterized in that: The silicon wafer is obtained by using the grinding apparatus according to claim 9.

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